Phosphorus implantation into in situ doped Ge-on-Si for high light-emitting efficiency

We investigated the optical, electrical, and structural properties of epitaxially grown Ge-on-Si substrates after phosphorous implantation. Ion implantation increases n-type doping in Ge for an on-chip light source. However, its effects on Ge should be carefully studied as implantation may increase the recombination sites, and possibly reduce light-emitting efficiency. We studied the light-emitting efficiency of implanted Ge using various material characterizations. We found that phosphorous implantation increased the doping concentration of in situ doped Ge-on-Si, which boosted the photoluminescence by 12-30%. It is therefore critical to optimize the post-annealing and implantation doses to increase light-emitting efficiency of Ge.